Field of the Invention
The present invention relates to apparatus for use in the oil industry, and, more particularly, to a reamer for use in oil well drilling operations.
Description of the Prior Art
Wellbore reamers are known in the field of oil well drilling operations, and are used to open wellbores to allow for smooth operation of the drilling string. For example, U.S. Pat. No. 8,607,900 to Smith discloses a bi-directional reamer. Similarly, European Patent Application No. EP1811124 by Bassal, et al. discloses a similar type of reamer.
While they are useful tools, these types of reamers have maintenance requirements that can result in increased costs in drilling. Wear and tear on the cutters or the tool body can result in effective failure of the tool, which can then require pulling the drill string to replace the reamer. Some wear of the cutting bits on a reamer is expected, but the rate of wear can be exacerbated by the configuration of the tool. For example, the configuration of the blades on a reamer may direct drilling fluid away from, rather than over, the cutting elements, resulting in excessive wear due to heating. Thus, it is desirable to provide improved fluid flow over the cutting elements of a reaming tool.
Additionally, current reaming-while-drilling tools utilize flat cap tungsten carbide inserts as the primary cutting elements on the cylindrical outer diameter. It is desirable to provide an improved cutting element design to provide such a tool with greater efficiency. Similarly, current reamer designs place the tungsten carbide cutting inserts in simple rows and columns, which does not provide uniform distribution of the carbide against the hole wall. It is desirable to provide a reamer that aligns the cutting inserts so that there is more uniform coverage of the blade width.
Current reamer designs also utilize blades that are helical in shape. It is desirable to provide a reamer with an improved blade design, for purposes of improving fluid flow over the cutting inserts.
Current reamer designs also provide polycrystalline diamond cutters along portions of the blades. However current designs fail to balance the load on these cutters. It is thus desirable to allow for the implementation of back rake and side rake with polycrystalline diamond cutters. Providing such back rake and side rake improves drilling efficiency by providing better force balancing and load work distribution of the cutters regardless of their position.